Taeniura lymmaFantail ray(Also: Lagoon ray; Ribbon-tailed stingray)

Geographic Range

Taeniura lymma, commonly known as blue-spotted stingrays, is found primarily in the Indo-west Pacific. They may be found in shallow continental shelf waters ranging from temperate to tropical seas. They prefer areas with sandy or sedimentary substrates in which they bury themselves. Sightings of Taeniura lymma have been recorded in Australia in shallow tropical marine waters from Ningaloo Reef, Western Australia to Bundaberg, Queensland. They can be found at depths of up to 25 m and have also been recorded to range in location from southern Africa and the Red Sea to the Solomon Islands. (Taylor, 1997)

Habitat

Taeniura lymma is found on sandy bottoms around coral reefs. These rays like to bury themselves just underneath the sand where they will feed on various invertebrates. They usually are found on shallow continental shelves; however, they have also been observed around coral rubble and shipwreck debris at depths of 20-25m deep. Divers and snokelers will often detect this ray by its distinctive ribbon-like tail poking out from a crack in the coral. These rays are most abundant inshore. (Allen, 1996; Taylor, 1997)

  • Range depth
    25 (high) m
    82.02 (high) ft

Physical Description

Taeniura lymma is a colorful stingray with distinct, large, bright blue spots on its oval, elongated body. The snout is rounded and angular with broad outer corners. The tail tapers and can be equal to or slightly less than the body length when intact. Its caudal fin is broad and reaches to the tip of the tail. At the tip of the tail are two sharp venomous spines which permit this ray to strike at enemies forward of its head. The tail of Taeniura lymma can be easily recognized by the blue side-stripes found on either side. It has large spiracles that lie very close to its large eyes. It can grow to a disc diameter of about 25 cm but has been reported as being as large as 95 cm in diameter. The mouth is found on the underside of the body along with the gills. Within the mouth are two plates, which are used for crushing the shells of crabs, prawns, and mollusks. (McEachran, 2004)

  • Range length
    95 (high) cm
    37.40 (high) in
  • Average length
    25 cm
    9.84 in

Development

When blue-spotted stingrays are born, they hatch out of egg cases and are pale gray or brown and are spotted with black or rusty red and white. These patterns and markings are distinct to each individual within a litter. As adults, they are olive-gray or gray-brown to yellow dorsally and white ventrally with numerous blue spots. When born, the young stingrays are about nine cm long and can grow to around 25cm as adults. The young are born out of egg cases with a soft tail that is encases in a thin layer of skin to prevent injury to the mother during birth. The skin is eventually lost and the tail is used as a protective mechanism. (Taylor, 1997)

Reproduction

Taeniura lymma is ovoviviparous. This means that the embryo is nourished by the yolk and the eggs are retained within the female until they hatch. The ray produces about seven live young in every litter. Each juvenile is born with the distinctive blue markings of its parents in miniature. In courtship, the male often follows the female with his acutely sensitive nose close to her cloaca in search of a chemical signal that the female will emit. Courtship usually includes some sort of nibbling or biting of the disc. The teeth of the male are used to hold the female in place during population. The male fertilizes the female via internal fertilization through the use of their claspers. The breeding season is usually in late spring through the summer and gestation can be anywhere from 4 months to a year.

Because only about seven live young are produced in each litter, this species is highly vulnerable to population collapses from overfishing, habitat loss and the pet trade. They also have a long gestation period making them even more susceptible to population collapse. (Taylor, 1997)

  • Breeding season
    late spring throught summer
  • Average number of offspring
    7
  • Range gestation period
    4 to 12 months

Lifespan/Longevity

The lifespan of Taeniura lymma is still unknown.

Behavior

Blue-spotted stingrays may be found alone or in small groups, mostly in shallow waters over reef flats. they are rather shy and will usually swim away rapidly if disturbed by divers. When threatened, blue-spotted stingrays will use their venomous tail to inject poison. The venom is produced and delivered into narrow groves running lengthwise along the underside of the stinger. The entire structure is covered by a thin layer of skin which, when broken, releases its venom into its victim. (Taylor, 1997)

Propulsion in Taeniura lymma is achieved using its pectoral fins which make up the bulk of its oval, disc shaped body. Blue-spotted stingrays have fin muscles which are found throughout the entire length of the fin. All of these muscles are active except at low speeds when they are not needed to propel the body through water. (Rosenberger, 1999)

Communication and Perception

Taeniura lymma uses electroreception to communicate with other members of its species. Blue-spotted stingrays,use strucutres called the ampullae of Lorenzini, which allow them to detect slight electrical impulses within the water. This electroreception is often used as a means of recognizing members of the same species. (Taylor, 1997)

Food Habits

Taeniura lymma has very distinct feeding behaviors. During high tide, it migrates in groups into shallow sandy areas of tidal flats to feed on sand worms, shrimps, hermit crabs, and small fishes. At low tide it recedes back into the ocean, usually alone to hide in the coral crevices of the reef. (Taylor, 1997)

Blue-spotted stingrays will feed on many things such as bony fish, crabs, shrimp, polychaetes and other benthic invertebrates. Since the mouth is located on the underside of the body, food is trapped by pressing the prey into the substrate with their discs. The food is then directed into the mouth by maneuvering the disc over the prey. (McEachran, 2004)

Taeniura lymma can detect its prey through an electroreceptor system. The nostrils are partly covered with a broad fleshy lobe, known as the internasal flap. This is covered in sensory pores and extends to the mouth. These pores form part of the ampullae of Lorenzini (the electrorecption system.) This electroreceptor system can detect electrical fields produced by the prey. This electroreceptor system cannot only be used to detect prey but can also be used to detect predators and other members of the same species. (Taylor, 1997)

  • Animal Foods
  • fish
  • aquatic or marine worms
  • aquatic crustaceans
  • other marine invertebrates

Predation

The most dangerous predator to blue-spotted stingrays are human beings. Blue-spotted stingrays are a popular ray to have in aquarium tanks. However, Taeniura lymma is very hard to take care of in an at-home aquarium. Besides humans, the only other type of predator known to this species of stingrays is the hammerhead shark. The hammerhead shark uses the cartilaginous projections form the side of their heads to pin them down to the bottom of the substrate while taking bites from the stingray's disc. The hammerhead is able to avoid being stung by the poisonous spines on the rays tail by pinning the stingray down. (Taylor, 1997)

Ecosystem Roles

Taeniura lymma plays an important role in their ecosystem. Taeniura lymma is a secondary consumer. It feeds on nekton such as bony fish. It also feeds on zoobenthos organisms including benthic crustaceans like crabs, shrimp/prawns, and worms such as polychaetes.

Economic Importance for Humans: Positive

Taeniura lymma is a popular aquarium pet. Their beautiful coloration makes them a prime candidate for an aquarium pet. In Australia, Taeniura lymma is often eaten and hunted for its meat. (McEachran, 2004)

Economic Importance for Humans: Negative

The sting that of blue-spotted stingrays may be very painful. (McEachran, 2004)

  • Negative Impacts
  • injures humans
    • bites or stings

Conservation Status

Although this species is very wide ranging and common, it is subject to human-induced problems because of capture by inshore fisheries and its attractiveness for the marine aquarium fish trade. Another major threat to this species is the destruction of its coral reef habitat. Without a habitat in which to live, this species may be pushed to extinction along with other species of the coral reef habitat. (McEachran, 2004)

Other Comments

The body of Taeniura lymma is made completely out of cartilage and contains no bone whatsoever. The stinging barbs on its tail can be regenerated if broken off. One interesting fact about the venom that is contained within the stinging barbs is that it can be broken down by heat. Therefore, if you ever encounter one of these magnificent animals and happen to get stung, immediately soak the wound in hot water in order to break down the venom and reduce the pain. Another interesting fact about Taeniura lymma is that it is one of the few species of rays that can retain their urine. (Webb, 1980)

Contributors

Matthew Wund (editor), University of Michigan-Ann Arbor.

Jennifer Miller (author), Western Maryland College, Randall L. Morrison (editor), Western Maryland College.

Glossary

Australian

Living in Australia, New Zealand, Tasmania, New Guinea and associated islands.

World Map

Pacific Ocean

body of water between the southern ocean (above 60 degrees south latitude), Australia, Asia, and the western hemisphere. This is the world's largest ocean, covering about 28% of the world's surface.

benthic

Referring to an animal that lives on or near the bottom of a body of water. Also an aquatic biome consisting of the ocean bottom below the pelagic and coastal zones. Bottom habitats in the very deepest oceans (below 9000 m) are sometimes referred to as the abyssal zone. see also oceanic vent.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

electric

uses electric signals to communicate

fertilization

union of egg and spermatozoan

internal fertilization

fertilization takes place within the female's body

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

motile

having the capacity to move from one place to another.

natatorial

specialized for swimming

native range

the area in which the animal is naturally found, the region in which it is endemic.

ovoviviparous

reproduction in which eggs develop within the maternal body without additional nourishment from the parent and hatch within the parent or immediately after laying.

pet trade

the business of buying and selling animals for people to keep in their homes as pets.

piscivore

an animal that mainly eats fish

reef

structure produced by the calcium carbonate skeletons of coral polyps (Class Anthozoa). Coral reefs are found in warm, shallow oceans with low nutrient availability. They form the basis for rich communities of other invertebrates, plants, fish, and protists. The polyps live only on the reef surface. Because they depend on symbiotic photosynthetic algae, zooxanthellae, they cannot live where light does not penetrate.

saltwater or marine

mainly lives in oceans, seas, or other bodies of salt water.

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

tactile

uses touch to communicate

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

venomous

an animal which has an organ capable of injecting a poisonous substance into a wound (for example, scorpions, jellyfish, and rattlesnakes).

visual

uses sight to communicate

References

Allen, T. 1996. Shadows In The Sea. New York, NY: Lyons & Burford, Publishers.

McEachran, J. 2004. "Species Summary for *Taeniura lymma*" (On-line). Accessed 11/05/04 at http://www.fishbase.org/Summary/SpeciesSummary.cfm?ID=5399&genusname=Taeniura&speciesname=lymma.

Rosenberger, L. 1999. Functional morphology of undulatory pectoral fin locomotion in the stingray taeniura lymma. Journal of Experimental Biology, 202: 3523-3539.

Taylor, M. 1997. Sharks & Rays. Sydney, AU: Time-Life Books.

Webb, 1980. Glutamine synthetase: Assimilatory roles in liver as related to urea retention in marine Chondrichthyes. Science, 208: 293-295.